1. Field of the Invention
This invention is directed to molded case circuit breakers, and in particular, to such circuit breakers in which a modular crossbar is used to assemble circuit breakers with a selected number of poles from standardized components.
2. Background Information
Molded case circuit breakers include for each pole a stationary contact and a movable contact forming a set of separable contacts. The movable contact is mounted on a moving conductor assembly which includes a contact arm having the movable contact affixed at a free end of the arm. The other end of the contact arm is supported by a contact arm carrier for rotation between a closed and an open position of the contacts by a spring powered operating mechanism. All of the poles in a multi-pole molded case circuit breaker are connected by a crossbar so that a single operating mechanism opens and closes the separable set of contacts of all of the poles simultaneously. Typically, the crossbar is a molded bar which is formed integrally with part of the contact arm carrier. Different composite molded parts are provided for two, three and four pole molded case circuit breakers.
There is a need to reduce the cost of manufacturing and assembling molded case circuit breakers.
There is a particular need for molded case circuit breakers which can be assembled with a selected number of poles from standardized parts.
There is a related need for such a molded case circuit breaker in which the standardized parts connecting the individual poles are robust enough to transmit the required torque from the common operating mechanism to the individual poles.